CC2420
SWRS041B Page 77 of 89
FSTST0 (0x27) - Frequency Synthesizer Test Register 0
Bit
Field Name
Reset
R/W
Description
15:12 -
0
W0
Reserved, write as 0
11 VCO_ARRAY_SETTLE_LONG
0 R/W
When '1' this control bit doubles the time allowed for VCO
settling during VCO calibration.
10 VCO_ARRAY_OE
0 R/W
VCO array manual override enable.
9:5 VCO_ARRAY_O[4:0] 16 R/W
VCO array override value.
4:0 VCO_ARRAY_RES[4:0]
16 R
The VCO array result holds the register content of the most
recent calibration.
FSTST1 (0x28) - Frequency Synthesizer Test Register 1
Bit
Field Name
Reset
R/W
Description
15 VCO_TX_NOCAL
0 R/W
0 : VCO calibration is always performed when going to RX or
when going to TX.
1 : VCO calibration is only performed when going to RX or when
using the STXCAL command strobe
14 VCO_ARRAY_CAL_LONG 1 R/W
When ‘1’ this control bit doubles the time allowed for VCO
frequency measurements during VCO calibration.
0 : PLL Calibration time is 37 us
1 : PLL Calibration time is 57 us
13:10
VCO_CURRENT_REF[3:0] 4 R/W
The value of the reference current calibrated against during VCO
calibration.
9:4 VCO_CURRENT_K[5:0]
0 R/W
VCO current calibration constant. (Current B override value
when FSTST2.VCO_CURRENT_OE=1.)
3 VC_DAC_EN
0
R/W
Controls the source of the VCO VC node in normal operation
(TOPTST.VC_IN_TEST_EN=0):
0: Loop filter (closed loop PLL)
1: VC DAC (open loop PLL)
2:0 VC_DAC_VAL[2:0]
2 R/W
VC DAC output value
FSTST2 (0x29) - Frequency Synthesizer Test Register 2
Bit
Field Name
Reset
R/W
Description
15 -
0 W0
Reserved, write as 0.
14:13
VCO_CURCAL_SPEED[1:0] 0
R/W
VCO current calibration speed:
0: Normal
1: Double speed
2: Half speed
3: Undefined.
12 VCO_CURRENT_OE
0 R/W
VCO current manual override enable.
11:6
VCO_CURRENT_O[5:0] 24
R/W
VCO current override value (current A).
5:0
VCO_CURRENT_RES[5:0] 32 R
The VCO current result holds the register content of the most
recent calibration.
